#include <iostream>
using namespace std;
int main()
{
int i=0;
float n,pjfen,sum=0.0;
cin>>n;
while(n!=-1)
{
i++;
sum=n+sum;
cin>>n;
}
if(i!=0)
{
pjfen=sum/i;
cout <<"平均分:"<<pjfen;	
}
return 0;	
}
